Rational thromboprophylaxis in medical inpatients: not quite there yet.

Routine thromboprophylaxis in hospitalised medical patients is based on trials that predominantly use asymptomatic deep vein thrombosis (DVT) as the endpoint. As asymptomatic DVT is 10-30-fold more common than symptomatic DVT, this exaggerates estimates of benefit and cost-effectiveness. Based on symptomatic disease, the number needed to treat per venous thromboembolism (VTE) prevented is high (150-1600), and the true cost-effectiveness of thromboprophylaxis for symptomatic event reduction is uncertain. The incidence of major bleeding among patients receiving prophylaxis is at least equal to the reduction in clinical VTE. Routine thromboprophylaxis in hospitalised medical patients is not warranted, and better patient selection is needed.